Anyone tried this 4,000 rpm tach in their slant nose IDI?

[Ford F834]

There have been a few threads around lately with guys looking for a factory diesel tach for their 83-86 slant nose IDI's. A good friend of mine has been searching for one, and I came across an odd ball 0- 4,000 rpm tach in a 1980 F700 with either a 370 or 429 gas V8 engine. I did a little reading and found out many of these larger trucks had 4,000 or 4,500 rpm tachometers in them. I guess some of the 300 I-6 owners have been seeking them out since they rarely rev above 3,500. My question is will this tach work and read correctly in an IDI? Has anyone ever tried one in their truck? I am a little ignorant about the signal from our IP gear magnetic pick up vs. the signal from a distributer. Just curious if anyone has made one of these work. Tach unit says EOTF-17360-Y and the gauge face says EOTF-17B316-B.

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[franklin2]

I would not think it would work, since the diesel tach gets many pulses per revolution off the gear, versus a gas tach which gets the number of cylinders divided by two pulses per revolution.

 

[Ford F834]

Yeah, I'm trying to find info on how the IDI sensor works, it is looking like a 53 tooth gear that rotates once for every two crank revolutions, so 26 pulses compared to 4. Not going to work.

 

[BDOGONE]

Does the pick-up measure each toolt, or just one embedded magnet?


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[Ford F834]

Does the pick-up measure each toolt, or just one embedded magnet?

It measures the teeth, or valleys depending on how you want to look at it. There are no magnets in the IP gear. 8.2L Detroit diesel trucks took their tach signal from the flywheel teeth I believe. Same basic idea.

 

[LCAM-01XA]

Rooster Booster over on Pirate made a bracket that puts a sensor inside his crank pulley, it reads off the pulley bolts (4 of them). That would give you the 4 pulses per rev that you need.

 

[Ford F834]

Rooster Booster over on Pirate made a bracket that puts a sensor inside his crank pulley, it reads off the pulley bolts (4 of them). That would give you the 4 pulses per rev that you need.

Very interesting... I will have to see if I can find details on how he did that... thanks for the tip!

 

[LCAM-01XA]

It's in the Tow Rigs and Trailers, his thread is something like "Fawk it I'm building a classic truck", pics were on last page where he shows off his dash and gauges first. He said he hasn't got the tach to work quite right yet, but i'm left with the impression it just needs to be adjusted on the back for proper pulses per rev.

 

[Ford F834]

Again, thanks. That was what I needed to find the thread...

http://www.pirate4x4.com/forum/tow-...wk-i-think-i-m-building-vintage-truck-92.html

Also dug up quite a few other threads while looking. Many diesel swappers ask that question "how do I get my gas tach to work with diesel" and they are all variations on this theme. ~Very useful clue. Thanks!

 

[LCAM-01XA]

His build is quite impressive, even more so since he's using an IDI to motivate that beast. The only possible problem I see with that sensor setup would be how the engine moves in the mounts, I'd suggest devising a way to attach the sensor bracket to the engine itself somehow.